Shader入门精要笔记 - CH7.3_渐变图控制漫反射

左边是使用了前面提到的SpecularPerPixel，中间是没加渐变图时，右边是加了渐变图

高光+渐变图漫反射(RampTex)

Shader "My/Tex/RampTexture"
{
    Properties
    {
        _Color("Diffuse Color", Color) = (1, 1, 1, 1)

        _RampTex("Ramp Tex", 2D) = "white" {} //渐变贴图

        _Specular("Specular", Color) = (1, 1, 1, 1) //高光反射颜色
        _Gloss("Gloss", Range(8.0, 256)) = 20 //高光区域大小
    }
    SubShader
    {
        Tags { "LightMode" = "ForwardBase" }

        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "Lighting.cginc"

            struct appdata
            {
                float4 vertex : POSITION;
                float3 normal : NORMAL; //顶点法线
                float2 texcoord : TEXCOORD0;
            };

            struct v2f
            {
                float4 vertex : SV_POSITION;
                float2 uv : TEXCOORD0;
                float3 worldNormal : TEXCOORD1;
                float3 worldPos: TEXCOORD2;
            };

            fixed4 _Color;

            sampler2D _RampTex;
            float4 _RampTex_ST;

            fixed4 _Specular;
            float _Gloss;

            v2f vert(appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.worldNormal = UnityObjectToWorldNormal(v.normal); 
                o.worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;

                o.uv = TRANSFORM_TEX(v.texcoord, _RampTex);
                return o;
            }

            fixed4 frag(v2f i) : SV_Target
            {
                fixed3 worldNormal = normalize(i.worldNormal); //顶点法线(世界空间)
                fixed3 worldLightDir = normalize(UnityWorldSpaceLightDir(i.worldPos)); //光方向(世界空间)

                fixed3 ambientColor = UNITY_LIGHTMODEL_AMBIENT.xyz; //环境光

                fixed halfLambert = 0.5 * dot(worldNormal, worldLightDir) + 0.5; //半兰伯特公式
                fixed3 rampDiffuseColor = tex2D(_RampTex, fixed2(halfLambert, halfLambert)).rgb * _Color.rgb; //采样渐变图
                fixed3 diffuseColor = _LightColor0.rgb * rampDiffuseColor;

                fixed3 worldViewDir = normalize(UnityWorldSpaceViewDir(i.worldPos)); //顶点到相机的观察方向向量

                fixed3 halfDir = normalize(worldLightDir + worldViewDir); // blinn模型引入的h向量
                fixed3 specularColor = _LightColor0.rgb * _Specular.rgb * pow(max(0, dot(worldNormal, halfDir)), _Gloss); // blinn模型高光反射计算公式(更亮, 高光区域更大)

                return fixed4(ambientColor + diffuseColor + specularColor, 1);
            }
            ENDCG
        }
    }
    Fallback "Specular"
}